Pipeline, Flow, or Chain? Picking the Right Tool to Wire LLM Calls Together

In the previous post I argued that agents are great planners and DAGs are great executors . This one is the practical follow-up: when you actually sit down to wire several LLM calls together, what tool do you reach for? Because the moment one prompt's output feeds the next, you've built a workflow — whether you call it that or not. download transcript → summarize → translate (tool) (LLM) (LLM) That tiny pipeline is already the whole problem in miniature: a non-LLM step (fetch a YouTube transcript), then a model call, then another model call that depends on the first. Run it as one giant prompt and you lose visibility; split it into steps and you gain debuggability — at the cost of more calls and more state to manage. The naming trap Half the confusion is vocabulary. The same idea ships under a dozen labels: Name What it whispers Chain sequential, output → input Pipeline stages, data flowing through Flow branches and conditions Workflow general orchestration Agent workflow the model also decides The word sets expectations. "Chain" promises a straight line; "agent workflow" promises the thing might re-plan on you mid-run. Pick the label that matches how much autonomy you're actually handing over — calling a deterministic two-step pipeline an "agent" only invites disappointment. The real choice: library or orchestrator? There are two families of tools, and they solve different problems. LLM-native chaining libraries — LangChain , LlamaIndex Workflows , Azure Prompt Flow , or visual layers like Flowise . These understand LLM-specific concerns out of the box: prompt templating, passing context between steps, token budgets, streaming, retries on a flaky model. General orchestrators — Airflow , Prefect , AWS Step Functions , Azure Logic Apps . These treat each LLM call as just another task in a DAG, and give you the heavyweight reliability machinery: durable state, scheduling, checkpointing, audit trails, human approval. The rule of thumb that falls out of the last post: F